Sony released the Android 5.1.1 Lollipop OS for the US variant of the Xperia Z Ultra, so now you should be running on the new 14.6.A.0.368 software. However, since we are talking about an OTA, you can receive the mentioned notification only if you are already on stock firmware and only if your phone isn’t rooted. Moreover, if you do manage to get the .ftf update file and flash it manually through FlashTool, the root access will be revoked as your phone will be restored back to its initial state.

So, you might have a hard time in deciding what to do: keep the root access and use an outdated version of the Android system, or revoke root and update to latest 14.6.A.0.368 Lollipop OS. Well, what do you say about getting a pre rooted stock Android 5.1.1 Lollipop OS instead off all that? In this way you can maintain the root access while updating your Xperia Z Ultra to latest and stock Lollipop software, so there is a win-win situation.

However, in order to do so, your Xperia Z Ultra should be already rooted and installed with a custom recovery image like TWRP or CWM recovery – the Android system doesn’t matter though. You see, the pre rooted OS about which I am talking about has been developed by those of xda-developers. It represents the stock Android 14.6.A.0.368 Lollipop 5.1.1 OS that was slightly modified into a .zip file from a .ftf package. Of course, root has been added while the proper system, once flashed, will remove the US carrier brand from your Sony Zperia Z Ultra.

Bottom line, you are installing a custom ROM that brings the stock Lollipop firmware on your Z Ultra. So, this is partial an official and unofficial update operation – even though you will be ending by using the official 14.6.A.0.368 Lollipop 5.1.1 Android OS, you will keep root access and you will be able to tweak your devices by performing further unofficial operations like flashing custom ROMs, removing bloatware, overclocking the CPU, making Nandroid backups, upgrading the battery life, bump the speeds, customize the UI and so on.

Good; so now you know why and when to use this dedicated step by step guide. Now just remember that you are going to flash a .zip file so a custom recovery image like TWRP or CWM recovery must be already installed on your Sony Xperia Z Ultra – else you won’t be able to use the pre rooted Android 5.1.1 Lollipop firmware.

This is a manual update procedure, so a computer must be used; your phone and its USB cord must be near too. Then, you should consider in applying the general pre requisites that are usually mentioning: temporarily turn off antivirus protection from your computer (else you might be interrupted while you try to download the update package); enable Developer Options on your phone as USB debugging must also be checked (tap several times on Built Number and then access “menu – settings – developer options”); charge your smartphone if the battery status shows less than 50% power left (if you skip this process you can end up in bricking your phone – if it gets turned off in the middle of the installation procedure).

When updating your phone your data might get corrupted or even erased. Well, when updating with a custom ROM actually a hard reset is implied (and clearing cache will also be there). So, in our case, backing up your data shouldn’t be an option for you – if you don’t sync your data, you will end up in losing your images, videos, audio files, market apps, calendar info, saved passwords, call logs, texts, contacts, internet settings, IMEI / NVRAM and everything else you have recently saved your Z Ultra. Bottom line, use cloud storage platforms, backup and restore apps and any other similar tools and backup your phone before updating to Android 5.1.1 Lollipop OS.

Finally, remember that this 14.6.A.0.368 pre rooted ROM is compatible only with the US version of the Sony Xperia Z Ultra that’s installed with a custom recovery image – try not to mess things up as you can easily brick or damage your Android device.

From recovery, first of all you have to wipe data and clear cache; so select “wipe data factory reset” followed by “wipe cache partition” and by “wipe dalvik cache”.

Return to main menu of recovery and from there select “install zip from SD card” and “choose zip from SD card”.

Pick the Lollipop firmware file and resume the update process.

When done, from main menu of recovery select “reboot system now”.

That was all; now you should be able to enjoy the new stock Android 5.1.1 Lollipop 14.6.A.0.368 firmware with root privileges on your own Sony Xperia Z Ultra. Do share your experience with other users too by using the comments field from down below.